News: Flat-Plane Crank Conversion

Flat Funding

You can crowdfund a FPC conversion for Coyotes and other V-8 engines

By Steve Turner
Photos courtesy of Stevie’s Crazy Garage

With all the hype surrounding the Flat-Plane-Crank 5.2-liter engine in the new Shelby GT350, you might be wondering if there’s a way to add that high-winding personality to your existing engine combination. As it turns out, Stephen Gray of Stevie’s Crazy Garage has done more than thought about it. He has spent the time to design flat-plane-crankshaft conversion kits for a variety of American V-8s, including the Coyote 5.0-liter.

Should Stevie’s Crazy Garage’s project get funded, the company’s FlatFast flat-plane-crank conversion kits will include the crank, rods, pistons, cams, damper, and bearings. These units will be designed for race-only applications and are kits are tuned for their intended block application.

Now Stephen wants his company to bring these kits to market for the Coyote and Brand X small-blocks. If they are well received, he has designs on other American V-8s. But for those new to the FPC crank dynamic, these rotating assemblies are lighter than a traditional crankshaft, they deliver a unique exhaust note, and they extend the powerband.

“The basic difference is that the power band is moved to a higher rpm level. Instead of making shifts at 7,000 or 8,000 like NASCAR, you make them at 8,500 or 9,000 rpm,” he said. “This will mean less shifting on the track. This is why Ford built the Voodoo and probably why Ferrari still uses them. I have nothing against the cross-plane crankshaft. I have built hundreds of them, but this kit will give racers another path.”

Here Stephen gives you a breakdown of the differences between the traditional cross-plane crankshaft and the flat-plane crankshaft for those that might want to choose this path…

So, why hasn’t this crankshaft design proven more popular? Well, the downside of the FPC is that it creates some aggressive harmonics that can be difficult to dampen. However, Stephen believes that today’s hardware and technology have paved the way for FPC durability and acceptance.

“I feel that the approach to flat-plane cranks here in America is based in the work Smokey Yunik did in the ’50s and ’60s: ‘You can’t do it, it is not worth the effort, and the vibrations will break the block in two.’” Stephen explained. “For the last three years, I have been researching this almost daily. Sometimes at an impasse with my current job designing supercomputers. The rotating assemblies that are being produced today are nothing like what was available in the ’50s and ’60s. The much required harmonic dampers are much better. So after all this research, the bottom line is that most of the vibration can be eliminated if the weight of the components and length of the lever arm (stroke) is bound by design. The engines should easily reach 8,500 to 9,000 rpm with the lighter flat-plane crank.”

If funded, the first FlatFast Crankshaft Kits will be built for Ford Coyote and Brand X small-block applications. However, if they prove popular, Stevie’s Crazy Garage intends to add other American and foreign V-8s, streetable FlatFast kits, and optimized intake manifolds to its repertoire. The company also plans a separate crowd-funding campaign to develop carbon-fiber panels for his prototype racer.

With that in mind, Stephen plans to address those issues by using top-shelf components and paying close attention to the little details to dial in these kits.

“The rod ratio (in the FlatFast kit) matches the Ferrari 480 at 1.77, but I may need to back this off a tad after I build the first few for torque purposes. The higher rod ratio reduces the nasty torsional harmonics that have given the flat-plane crank a bad name,” Stephen explained. “The Ford Voodoo (although I do not know for sure) will have a 1.63 rod ratio. It amazes me that they are able to control the harmonics at all, plus they are using an up, down, up, down configuration which makes it even harder to iron out the vibes, but they are Ford and have lots of capital and supercomputer time.”

Of course, the trick for a small outfit to create an expensive product line like these requires a lot of capital. To take his FlatFast crankshaft kits from dream to reality, Stephen is utilizing a thoroughly modern technique—crowdfunding. He plans to use Indiegogo to allow fellow FPC enthusiasts to chip in and fund the further development of the project.

“If the baseline crowd-funding goal is met, I will create four research crankshaft kits. Those mentioned previously, with the addition of a Boss 302 show car engine,” Stephen added. “To advertise and debug the kits, I will build an RCR Superlite to race at the Texas Mile and other notable races. I hope the kits will be available late 2016. I am a little behind the Ford Voodoo engine, but I will have more kits than just the one block.”

As is typical with these type of campaigns, there are various tiers, some low-priced options for those that just want to help out and other more costly levels for those that want the finished product first.

“The crowd-funding is set up by levels: contribute $5 and you get to follow the action on the website. Contribute $20,000 and you get a flat-plane kit,” he explained. “The levels vary with those as the starting and end points. The levels are also setup like a race team—Team Support, Pit Crew, Team Driver, and SCG Fellow.”

If you would like to support the effort or just learn more about the FlatFast Crankshaft Kits, you can check out the Indiegogo page right here. If it gets funded the FPC kits are due for release in late 2016.